Thermionic valve



April 23, 1929. w may 1,710,328

THER'MIONIC VALVE Filed Feb. 19, 1927 IYIVVEIVTOR HARV/E W WH/TB) BY @xrf ATTOR/V Patented Apr. 23, 1929.

HARVIE W. WHITBY, 'OF IRVINGTON, NEW J 'rnnnmroivrc VALVE.

Application filed February 19, 1927. Serial No. 169,664.

This invention relates to means whereby alternating current may be used for heating the filament of a thermionic valve, particularly when used in radio work.

It is the general practice at the present time to vuse a steady source of direct current, such as a storage battery for heating the filaments of thermionic tubes or valves. If alternating current is applied to the filament of a standard electron tube or thermionic valve, as used in the ordinar tuned radio frequency or neutralized set, t 1e alternating current hum is picked up and amplified by the tubes, so as to interfere with the reception of the radio signals.

It is therefore the principal object of my invention to provide means built in as a part of the tube or valve, which will enable alternating current to be used directly on the filament of the tubes. I

Another object of my invention is to provide an arrangement by which the present day sets, employing so called tuned radio frequency or neutralized circuits, etc., may be readily converted from a battery operated set to one in which alternating current may be used.

The advantage of using alternating current direct from the house lighting sockets without the use of any storage batteries or dry cells is clearly apparent, and to do away with these batteries is of course an ancillary object of my invention.

When alternating currentis used on the filament of a thermionic valve, I have found that means must be taken to provide a neutral return for the electron circuits within the valve, for example the grid and plate circuits as well as to provide a neutral ground for the filament circuit.

My invention will be clearly understood by reference to the annexed drawingwhereln Figure 1 is a diagrammatic view of a thermionic valve incorporating one form of my improvement.

Figure 2 is a partial diagrammatic view of a typical radio receiving set.

Figure 3 is a diagrammatic View similar to Figure 1 wherein the circuits of the thermionic valve are illustrated ready to be applied to the socket as shown in. Figure 2.

Figure 4 is a view similar to Figure 8 of a modified form of arrangement.

In the different views, wherein like members refer to corresponding parts, 1 illustrates the envelope or evacuated bulb comprising the thermionic valve. Within the bulb or tube 1, there may be mounted any required number of elements, and by way of illus tration but not of limitation, a grid 4: is illustrated and a plate 3 together with a filament 5. The base 2 of the valve carries a terminal 9 connected to the grid at and a terminal 10 connected to the plate 3. Mounted within the tube 1 is a resistance 8 having its terminals connected to the ends of the filament 5. At 1 the electrical center 13 of the resistance 8, a tap 14 is taken to the exterior of the valve, and connected to the terminals 11 and 12, which are ordinarily and usually used to receive connections from the terminals of the the valve in the usual way. As is usual in'a hook-up ofthis character the battery B is connected with a rheostat 19, with the filament 5. and the plate 3 is connected to thewinding 21 associated with the winding 22 and tuning condenser 23, extending to a succeeding valve. Feeding the plate circuit is a' source of energy 20 which may be a battery or a socalled B-eliminator, the circuit being completed by the connection 24.

When it is desired to convert the set shown in Figure 2 to one utilizingalternatiug current on the filament all that is necessary, is to disconnect thebattery B and insert the tube having .the connections as illustrated in Figure 3, connecting of course alternating current to the wires 6 and 7 of the valve. By introducing the resistance 8 into the valve either within the tube 1 or within the base structure, and by using the central tap 14 in the manner shown, I am able to provide a neutral return for all of the electron circuits within the valve and consequently there is substantially no alternating current hum produced in the arrangement shown. In Figure 4 it is contemplated the resistance 8 may take the form of a filament comprising a considerable resistance, it being understood that alternating current of the proper voltage is to be applied to the terminals 6 and 7 for heating the resistance 8. whereby the same will give off the required flow of electrons. While I vention into practice may be varied considerably from the diagrammatic illustrations shown in the drawing.

It is to be understood that the thermionic valve disclosed herein may be used for other purposes besides radio work, where such arrangements involve the use of a thermionic valve.

Having thus described my invention, what I claim is 1 A thermionic valve for utilizing alternating current on the filament thereof comf prising; a base on the valve having the usual four terminals, one for the plate circuit, one for the grid circuit and two such as are usual ly used for the filament. circuit, a pairof special terminals for the filament of the valve, a resistance mounted within the valve and connected across the filament terminals and a tap at the electrical center of the resistance brought out and connected to said two usual filament terminals.

2. A thermionic valve having; a grid, a plate and an element adapted to give ofi electrons, said grid and plate having connections brought out to the usual terminals, and terminals on the valve positioned and corresponding to the usual two battery terminals,

rasse of the thermionic tubes, to sets using alternating current on said cathodes comprising; a new thermionic tube to fit the old tube socket in use in the set, said new tubehaving; a grid, plate and cathode with connections from the grid and plate brought out of the usual terminals, a pair of special terminals for the cathode, terminals on the tube positioned and corresponding to the usual battery terminals and a tap at the electrical center of the oathodebrought out and connected to said usual battery terminals.

4. A thermionic tube having a base with the usual four terminals thereon; to wit, one for the grid, one for the plate, and two corresponding to the usual direct current terminals, and also having at least a grid, a plate,

and an electron emission means, said grid and plate being connected to their said respective base'terminals, while the two usual direct current terminals are connected together, a

pair of special terminals for applying alternating current to the electron emission means,

and means for providing a neutral return for the electron circuits through the tube comprising; a tap at the electrical center of said electron emission means, said. tap being brought out to the said two terminals that are connected together,

In testimony whereof, I affix my signature.

HARVIE W. WHITBY, 

